Technical terms

What is an IP address? IP, or Internet Protocol, is the numerical address that every computer on the internet has. The IP address can also reveal the computer's location

What is file sharing? File sharing is a means of sharing content (e.g. films, songs, pictures) across the internet

What is illegal file sharing? If a copyright owner believes its content has been shared without its permission, it can apply to court for a Norwich Pharmacal Order claiming breach of copyright. If granted, this means it could force internet service providers to share contact details of the IP address holder who appears to have breached copyright

Hatton & Berkeley, which provides financial services to small businesses, sent the letters on behalf of its client TCYK LLC to Mrs Drew.

Robert Croucher, managing director of Hatton & Berkeley, said: "They [the letters] are part of what's referred to as a pre-action protocol. We send them before action...They don't actually make a demand for money."

In a statement, Sky said: "TCYK LLC successfully applied for a court order against Sky, which means we have been ordered to supply the details of some of our account holders that match the list of IP addresses they have identified."

IT expect Craig Sharp said: "Most likely the outcome is that somebody has been able to use her [Mrs Drew's] wi-fi signal."